I like to go light, but there are people out there who take the concept to the extreme. Exhibit A would be the Arctic 1000, an unsupported 1,000 kilometer/621 mile traverse of the Alaskan backcountry.
Three men started and on July 4, after 24 days of voluntary self-abuse, one man finished: long-time Alaskan and world wilderness adventurer Roman Dial. While the expedition’s web site is a bit hype-heavy, for example stating that "a team" completed the traverse when Dial was the sole finisher, it was a magnificent undertaking and a true test of ultralight gear.
Pictured above is a custom dry-bag backpack used by the expedition, manufactured by ULA Equipment.